Looks like both system shows "disabled"
 I used this little software : 
http://milek.blogspot.it/2010/02/zvols-write-cache.html
 What makes me worried now is that I discovered that 2012 kernel is NEVER using 
zil (used zilstat) on iscsi vols with sync=standard, as if the system is using 
RAM for caching because those vol are fast as hell!
 Instead, the new kernel uses zil with sync=standard, but looks too slow behind 
two 10GB ethernets.
 I'm starting to get really confused...
 Does it means I should set sync=always on older kernel to force those iscsi to 
sync on zil?
 In this case I will go down to the performances of the new kernel?
 
----------------------------------------------------------------------------------
 Da:  Yuri Pankov
  [email protected]
 Data: 8 luglio 2015 19.33.28 CEST
 Oggetto: Re: [discuss] iscsi sync=standard changed?
 On Wed, 8 Jul 2015 16:18:58 +0200 (CEST), Gabriele Bulfon wrote:
 Hi,
 I think I've found why an April 2012 kernel shows faster response on
 iscsi than a Dec 2014 one.
 Looks like the iscsi sync=standard works almost like disabled on the old
 one, while almost like enabled on the new one.
 Obviously, justs by adding the zil to the new one will let the iscsi
 work as expected.
 I was just trying to guess why the two systems were acting different on
 the same config without zil.
 So, my question is:
  is the sync=standard of iscsi vols changed since Apr 2012, so now it
 syncs much more than before?
  can I be safe on installed machines with old kernel, where iscsi-vols
 have sync=default, syncing less, but having a zil?
 This commit *could* be related, check if the wcd settings of your ZFS
 volumes differ between the systems:
 
https://github.com/illumos/illumos-gate/commit/7e0955bbb1c326d78038afe0d108c8ae4934a78a



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